The Nine Springs plant is designed to treat wastewater,but the District has an interest in protecting all water since it is connected – from rain to groundwater to wastewater to lakes and streams. Just as we work to prevent pollution in wastewater, we work to prevent polluted runoff. The stormwater retention ponds out here help protect water that hasn’t gone down the drain.


Each of these basins has its own purpose. The first basin captures sediment, which can pollute water bodies when it runs off of surfaces. The second basin allows for water to trickle down into groundwater, a process call infiltration, which recharges the water supply. In this area, we get our drinking water from groundwater wells, so keeping groundwater clean and plentiful is crucial.



Like other features inside the maintenance facility, these basins use renewable sources from the treatment plant. In addition to recovering clean water from wastewater, we also recover solids which are converted into fertilizer products. Most solids are turned into MetroGro, a fertilizer that is applied to farm fields. But solids can also be further refined into a product called MetroMix, which is a mixture of the biosolids with sand and sawdust to make a soil-like material. MetroMix is a higher-quality material than MetroGro and can be used like garden soil. MetroMix was used for planting vegetation in the basins, which helped save money and energy on planting and materials transportation.


These basins also use prairie grass as native vegetation to retain stormwater. There are additional native plants along the exterior of the building to absorb rainwater as well. The outside of the building includes “rain chains” that direct rainflow from the roof to the vegetated areas below.

No potable water is used to irrigate the landscape around this building.